There is usually an undisclosed time limit when it comes to networking, especially if you are in a networking event. General rule of thumb is, if you start running out of content, it is a good idea to give others a chance to interact as well. However, if you feel that you have something productive to contribute, or you feel that you need to get to know someone better, stick around as long as you are not making the other party uncomfortable. Otherwise, close off by telling the person that you enjoyed meeting. At this point you should have already exchanged contacts.
This is by far the most crucial part of any networking encounter. It does not make sense to go to a networking event, establish a contact and then never follow through afterwards. The initial follow through should NEVER be an immediate request for a favor. Nothing breaks apart a potential networking relationship than only calling when you need something. Remember, networking is all about cultivating beneficial relationships. Thus said, you have to act fast, before you disappear from memory and build up on the initial meeting. Realize that even at this point you still have to maintain a high level of professionalism, so do this in a proper and professional manner.
A good follow through conversation should basically reiterate key points from earlier discussions and leave an open ticket for future correspondence. Ideally, you should seek a face-to-face meeting, but please do this tactfully.
Since networking is, at its most basic level, the building of mutually beneficial relationships, it is important to nurture those relationships beyond business. This could initially be in the form of subtle communications such as Christmas cards, gift certificates etc. As the relationship progresses, you can move on to bigger and better things.
You should never be afraid to utilize your networking contact on anything within the realm of their abilities. Such connections might be in the form of job referrals, introductions or help in furthering a particular business agenda.
When you have established that the individual is the proper resource for the type of connection you are seeking, approach them and articulate your request. If you have nurtured a good relationship, then the rest should be easy.
The most adept networkers know how to convey appreciation for networking favors. If someone has been helpful to you, let them know that you appreciate it. A simple thank-you card should be sent to the person as quickly as possible.
When you are known as a strong resource, people remember to turn to you for suggestions. In the continuing nurture of the networking relationship make sure you make your contacts aware of your strong points and how you can help them. Whenever favors are requested of you, act on them quickly.